The present invention relates to a machine for mounting and dismounting tyres.
In order to perform a tyre dismounting and a following mounting operation off and on a wheel, the prior art comprises machines which include a self-centring device which enables the wheel to be blocked and to set it in rotation with respect to an axis, which in the majority of cases is a vertical axis, in proximity of which device there is a pair of debeader tools, an upper tool and a lower tool, arranged symmetrically with respect to the horizontal plane of symmetry of the wheel, and a second vertical column along which a dismounting tool can slide, as well as a mounting tool, both being associated to a relative work arm.
In the prior art, in order to perform the dismounting of the tyre from the wheel, the wheel is fixed on a self-centring device and blocked thereto. At this point debeader tools are first applied, by translating the first column; the debeaders are positioned in contact with a point of the two opposite circular edges of the tyres (beads) in order to push them internally of the rim, from which the beads then detach. Once the debeading operation is done, the debeaded tyre is removed from the rim (to which it is still associated). This operation is performed by using the dismounting tool located on the second column, which column is neared by translating to the wheel on the self-centring device. In this case too, the dismounting tool, which bears a hook at an end thereof, is brought close to the wheel into a position such that it can be inserted between the edge of the rim and the bead of the tyre up until it hooks the tyre, which is then extracted by completely detaching the tyre from the rim of the wheel itself.
In order to perform a mounting operation of a new tyre on the same rim, a mounting tool is used, also located on the second column, which consists in a bar which is brought into proximity of the bead of the new tyre, previously placed around the rim, to push it internally of the rim to which it must attach. All of these operations are performed while the wheel rotates on the self-centring device.
In order to operate correctly, in each of the above-described operations, i.e. the debeading, dismounting and mounting, the wheel and the tool to be used must time by time be in a reciprocal position such as to enable contact in a point located in proximity of the bead and thus the circular edge of the rim. The described known machines exhibit some drawbacks and disadvantages. Each time the three described operations are performed on a same wheel, the wheel and the tool under use have to be located in a reciprocal position such as to guarantee a correct performing of the work and since the tools are borne on two columns, both columns have to be moved so that the reciprocal position between the wheel and the tool used is the same each time.
Further, the presence of two columns limits the movement and vision of the operator in proximity of the zone in which the machine operates on the wheel, creating relative awkwardness and obstacles in relation to the freedom of movement of the operator himself.